1. Field of the Invention
A method of augmenting the cutting operation of a continuous mining machine by the optimum placement of high pressure water jets.
2. Description of the Prior Art
Two sources of patent literature provide what is believed to be the closest prior art. These are the two U.S. Pat. Nos. 3,272,940 (P. Belugou) and 4,025,116 (Roepke et al). In the former reference water is delivered and discharged . . . "to the rear of the cutting edge of the picks in the zone in which the dust is concentrated." (column 2, lines 8-11). The W. W. Roepke et al patent is really not concerned with the reduction of airborne respirable dust by the use of water jets but, it does disclose (see column 3, lines 51-65) the use of high pressure (10,000 psi or more) water jets located at the center line of the bits' points to precut holes or slots in the coal face.
Neither of these references disclose the same or a similar apparatus and/or method as that now being claimed whose main purposes are to reduce primary respirable dust generation, to reduce the energy required in the cutting operation; and to lower methane ignition potential from frictional heating. The invention to Belugou is concerned with reducing dust and cooling the cutting head but the water discharge outlet is not at or near the bit's cutting area or the need to control water volume. Additionally Belligou does not discuss the water pressures needed. The W. W. Roepke at al patent is concerned--as far as the high pressure water spray--with only kerf cutting clearance for the carbide bit tip, not with reducing dust or cooling the cutting bits. If the 10,000 or more psi cutting pressure were used, the coal would be cut in such a manner as to substantially increase total water volume at the face leading to potential soft bottom problems. This invention seeks to place the water around the tip of the bit with sufficient pressure to keep the nozzle opened during the cutting operation by using a pressure equal to or slightly less than the compressive strength of the coal being cut (less than 6,000 psi) in such a manner as will minimize water at the face area thus preventing soft bottom problems. This approach will make this invention amenable to a larger number of mines.